There was a lot to read and hear about Wikileaks recently. But I still don't know how Wikileaks protects its sources.

Sure, Wikileaks doesn't explain to the world how they make sure that anyone can handle in documents or whatever without the possibility to be identified. But I think (to people who know more about the topic than me) it is clear how the mechanism works more or less...

I know how TOR, SSL and PGP work, but how can Wikileaks realize its secure hand in of documents, videos, etc.?